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m a s s s p e c t r o m e t r y Finnigan™ GC-C/TC III GC Interface for Compound Specific Isotope Analysis Analyze • Detect • Measure • Control™ Finnigan™ GC-C/TC III GC Interface for Compound Specific Isotope Analysis Finnigan™ GC-C/TC III GC Interface for Compound Specific Isotope Analysis The Finnigan GC-C/TC III interface from Thermo Electron Corporation is a state of the art GC interface for the analysis of 13C/12C, 15N/14N, 18O/16O, and D/H. Organic compounds eluting from a GC column are converted into simple gases when traversing a capillary micro-reactor. Accordingly all compound specific isotope ratios can be analyzed in the IRMS. Thermo’s Finnigan GC-C/TC III Interface provides the highest performance attainable for: • Compound specific isotope analysis of δ13C, δ15N, δ18O, and δ2H • All GC-volatile organic compounds • Analysis into the picomole range • Highest GC resolution due to true capillary design • Quantitative high temperature combustion up to 1000 °C • Quantitative high temperature pyrolysis up to 1500 °C • Fractionation-free sample transfer • Highest transfer rate into the IRMS • Independent reference gas injection The first Finnigan GC combustion system for 13 C/12C (δ13C) determination was introduced in 1988, opening the new field of compound specific isotope analysis (CSIA). This technique combines the exquisite chemical resolution of capillary GC with the high precision of isotope ratio mass spectrometry (IRMS). Thermo Electron added the capability for analysis of δ15N in 1992 and δ18O in 1996. δD analyses by quantitative pyrolysis or High Temperature Conversion (GC-TC IRMS) was introduced in 1998, together with the development of the Finnigan DELTAplus XL, with an energy filter in the m/z 3 collector for the suppression of 4He+ ions, which otherwise corrupted the HD+ signal. The Finnigan GC-C/TC III incorporates the knowledge and experience that comes with having installed > 400 GC combustion and > 150 GC pyrolysis interfaces. Quantitative Combustion Quantitative Pyrolysis Finnigan™ GC-C/TC III GC Interface for Compound Specific Isotope Analysis GC Combustion Mode for δ13C δ15N All compounds eluting from a GC column are oxidized in a capillary reactor to CO2, N2, and H2O at 940 to 1000 °C. NOx produced in the oxidation reactor is reduced to N2 in a capillary reduction reactor. The H2O formed in the oxidation process is removed by an on-line, maintenance-free water removal system. For the analysis of δ15N, all CO2 is retained in a liquid nitrogen trap before transfer into the isotope ratio MS (IRMS) through the movable capillary open split. The Oxidation Reactor Quantitative oxidation of all organic compounds eluting from the GC column, including the refractory methane, is performed at temperatures up to 1000 °C. The reactor consists of a capillary ceramic tube loaded with twisted Ni, Cu, and Pt wires.1 The reactor can be charged and recharged automatically with O2 added to the Backflush flow every 2-3 days, depending on the operating conditions. The Backflush System The Finnigan GC-C/TC III is equipped with a Backflush system for eliminating all solvents in front of the oxidation furnace. The Backflush reverses the flow through the oxidation reactor towards an exit directly after the GC column to cut off all eluting solvent. All valves are kept outside of the analytical flow path to ensure the cleanest combustion conditions and leaving all GC related parts untouched, thus retaining the highest GC performance. 1 U.S. Patent 5,432,344 Principle of the Finnigan GC-C/TC III Interface in GC Combustion Mode The Reduction Reactor Water Removal The LN2 Trap (δ15N Mode) The reduction reactor is operated at 650 °C to remove any O2 bleed from the oxidation reactor and to convert NOx into N2. It is made of the same capillary design as the oxidation reactor using the same high precision, low thermal mass heater. The water produced by the oxidation reaction is removed through a 0.3 mm inner diameter NafionTM capillary, which is dried by a countercurrent of He. The water removal adds no dead volume and is maintenance-free. For the analysis of δ15N, all the CO2 must be removed quantitatively to avoid interference of CO+ (produced in the ion source) with the N2+ analyte. This is achieved by immersing the deactivated fused silica capillary between the water removal and the open split in a liquid nitrogen bath. The trapped CO2 is easily released (every 12–18 h) with no risk of CO2 contamination of the ion source by using the movable open split. The Movable Open Split For high precision isotope ratio determination, the ion source pressure must be kept absolutely constant. For this reason, each continuous flow system has to be interfaced to the IRMS via an open split. For the Finnigan GC-C/TC III we have developed a computer-controlled movable open split, which couples and decouples to the IRMS without changing the ion source pressure while being compatible to the strict requirements of GC capillary technology. The valve-free open split is absolutely inert and does not create any pressure waves. The open split in decoupled mode allows maintenance on the Finnigan GC-C/TC III interface, e.g. release of CO2 in δ15N mode, without any transfer of sample gas into the IRMS. During acquisition high backgrounds can automatically be cut off to place reference gas pulses, without any effect to the GC flow system. Principle of the Moveable Open Split Finnigan™ GC-C/TC III GC Interface for Compound Specific Isotope Analysis GC Combustion Mode Determination of 13C/12C Isotope Ratios Applications: Alcohols, alkanes, biomarkers, polyaromatics, steroids, FAME, methane and natural gas, chlorinated hydrocarbons, BTEX, amino acids, sugars, CO2, flavor compounds... Fatty Acid Methyl Esters (FAME, Standard Mixture), splitless injection, HP5 30m, 0.32 mm, 0.25 µm film thickness, oxidation @ 940 °C, reduction @ 650 °C Determination of 15N/14N Isotope Ratios Applications: Amino acids, flavors, amines, biomarkers, N-heterocycles, drugs, N2, N2O... N-Acetyl, amino acid propyl esters (NAP), splitless injection, Ultra2 50m, 0.32 mm, 0.52 µm film thickness, oxidation @ 980 °C, reduction @ 650 °C High Temperature Conversion Mode Determination of D/H Isotope Ratios Applications: Alcohols, alkanes, biomarkers, polyaromatics, steroids, FAME, methane and natural gas, BTEX, amino acids, sugars, flavor compounds... Alkanes (standard mixture), spliltess injection, CP-Sil8 CB low bleed 30m, 0.25 mm, 0.25 µm film thickness, high temperature reactor @ 1420 °C Determination of 18O/16O Isotope Ratios Applications: Alcohols, sugars, flavor compounds, phenols... Flavor mixture of 5-nonanone, g-octalactone, methyl salycilate, linalyl acetate, split injection 1/20, Ultra1 30m, 0.32 mm, 0.52 µm film thickness, Pt shielded high temperature reactor @ 1280 °C Finnigan™ GC-C/TC III GC Interface for Compound Specific Isotope Analysis High Temperature Conversion Mode δD and δ18O Quantitative pyrolysis by high temperature conversion of organic matter for the conversion of organic O and H to CO and H2 for δD or δ18O determination requires an inert and reductive environment at very high temperatures, to prevent any H or O containing material from reacting or exchanging with the analyte. For δD and δ18O determination, a high temperature reactor is mounted in parallel to the combustion reactor. Because quantitative conversion is achieved in the reactor, no additional clean up is required. The H2 and CO are passed through the inactive reduction reactor. The water removal step has no effect on the very dry analyte gas. The downstream part of the interface is kept in standby. The Shielded CO Reactor For the determination of δ18O, the analyte must not contact the ceramic tube which is used to protect against air, and for stability. The pyrolysis takes place in an inert platinum inlay. Due to the catalytic properties of the platinum, the reaction can be performed at 1280 °C. Depending on the number of C, O and H atoms in the molecule, CO and H2 plus a C deposit are formed. Although all organic structures can be converted with good GC performance and precision, some compounds show an offset, which requires internal referencing by compounds with a known isotope ratio. Principle of the GC-C/TC III Interface in High Temperature Conversion Mode Principle of High Temperature Conversion H2 C n H x Oy C CO The High Temperature H2 Reactor For the determination of δD from organic compounds, the reaction is performed in an empty ceramic tube at 1450 °C. Tests have shown that such high temperatures are required to ensure quantitative conversion.2 The use of a catalyst must be avoided to eliminate the risk of adsorption of H2, which would lead to temperature dependent 2 T. Burgoyne and J. M. Hayes, Anal. Chem. 70, 5136 (1998) Principle of Reference Gas Injection fractionation. The Finnigan GC-TC reactor is catalyst-free and therefore eliminates fractionation during high temperature conversion. Even CH4 can be converted with completely reproducible and linear results. Reference Gas Injections In IRMS, measurement of isotope ratios requires that sample gases be measured relative to a reference gas of a known isotope ratio. This is the only way to achieve the required high precision of e.g. < ± 1.5 ppm of 13C (0.15 ‰ in the δ -notation). For the purpose of sample-standard referencing, a cylinder of calibrated reference gas (H2, CO2, N2, CO) is used for extended periods of time. An inert fused silica capillary supplies the reference gas in the µL/min range into the miniaturized mixing chamber, the Reference Gas Injection Port. Under control of Isodat 2.0, this capillary is lowered into the mixing chamber for 20 s, creating a mixture of He and reference gas, which flows into the isotope ratio MS via a second gas line. This generates a rectangular, flat top gas peak without changing any pressures or gas flows. The use of reference gases reduces the operational costs while increasing the sample throughput. The reference gas consumption is negligible and thus gases can be kept trickling continuously, ensuring constant conditions in the supply lines and pressure regulators. Finnigan™ GC-C/TC III GC Interface for Compound Specific Isotope Analysis Options Capillary Gas Chromatograph The Finnigan GC-C/TC III Interface is equipped with Thermo’s Finnigan Trace GC with split/splitless injector and digital pressure and flow control (DPFC). The Finnigan Trace GC can be equipped with up to 2 injectors and 2 detectors and sub ambient oven cooling. Alternatively, the Finnigan GC-C/TC III Interface can be interfaced with an Agilent 6890 GC. GC Injectors The split/splitless injector offers the flash evaporation in an inert chamber with split or total sample transfer onto the capillary column. The design of the vaporization chamber ensures wide linearity even with relatively large sample sizes. The unmatched Finnigan Trace GC cold on-column injector gives access to a discrimination and thermal degradation free sample introduction directly into the capillary column with highest GC performance. The Finnigan BEST PTV offers programmable temperature vaporizing injection techniques. The injector can be operated in cold split, cold splitless, solvent split, as well as conventional isothermal split/splitless mode. The Finnigan Trace GC’s Large Volume Injection (LVI) technique combines the advantages of a cold on-column injection with sample volumes of up to 250 µL using a special pre-column and splitting valve in front of the analytical capillary column. GC Detectors The Finnigan Trace GC offers a wide range of detectors, e.g., Flame Ionization Detector (FID) and Pulsed Discharge Detector (PDD). The detector trace is monitored by Isodat 2.0 software. Autosamplers All injection modes can be automated by using one of the following autosamplers. The Finnigan AS2000 and AS3000 are used for all liquid injection modes with a liquid sample tray for 90 samples. The Finnigan AS2000 and AS3000 are fully integrated into the Trace GC concept. The GC-PAL offers liquid and gas headspace injections. The GC-PAL has a fully object oriented structure which allows free designing and positioning of sample trays. The Combi-PAL offers all advantages of the GC-PAL. In addition the Combi-PAL is upgradeable to heated headspace and solid phase micro extraction (SPME) injection techniques. Integrated quadrupole MS The conversion of the compounds into simple gases like H2, CO2, N2 or CO is mandatory for the high precision required for compound specific isotope ratio analysis. Subsequently any direct structural information of each compound is lost after this conversion. The integration of a quadrupole mass specific detector together with the Finnigan GC-C/TC III interface allows the parallel acquisition of structural information and high precision isotope ratio determination within a single GC analysis. GC/GC-C/TC IRMS Very complex compound mixtures in a GC sample may not be fully separated on a single GC capillary column. The coupling of two GC columns in the Finnigan Trace GC by the Finnigan MCSS (Moving Column Stream Switching) system gives access to the pre-separation of compound groups on a first GC column followed by a final high performance separation of a selected compound group on the second GC column. A second injector and two FID detectors are required. Finnigan PreCon Trace Gases Loop Injector Beside the standard split injection of gas volumes < 250 µL the Finnigan GC-C/TC III interface can optionally be equipped with a Gas Loop Injector with variable loop size for quantitative sample transfer for low gas concentrations, e.g. CO2 from air (360ppm), CH4 in mud gases (< 0.1%). For gas concentrations in the low ppm and ppb range the Finnigan PreCon gives access to the fully automated preparation and pre-concentration of trace gases like N2O (300 ppb), CH4 (1.7 ppm), etc. followed by a cryogenic focusing in front of the GC column. The Finnigan PreCon can be loaded manually or operates fully automated using the GC-PAL autosampler with a two line needle for continuous sample transfer. The GC-PAL can be equipped with a 96x10 mL sample tray. User-defined sample trays can easily be registered and automated due to the fully object oriented structure of the GC-PAL. All processes are controlled by user-definable Isodat 2.0 scripts. For additional information please contact your local Thermo Electron specialist and get in contact with our team of application specialists. Finnigan™ GC-C/TC III GC Interface for Compound Specific Isotope Analysis Isodat 2.0 Software Isodat 2.0 is a new software suite for system control, data acquisition and data evaluation. The advantages Isodat 2.0 offers for Finnigan GC-C/TC III applications include: • Easy and fast method and sequence setup for Isotope Ratio MS, GC and autosampler. • Complete control and automation of all interface functions during data acquisition. • Automated GC peak and background detection with a wide selection of dedicated detection and background subtraction algorithms. • Fully automated correction of the GC elution shift of isotopomers. • Fully automated H3+ correction of each single raw data point. • Fully automated ion correction for isobaric ion contribution such as 12C17O16O on 13C16O16O. • User defined ion correction formulas can be registered in Isodat 2.0 using the Isodat Script Language (ISL). • Full access to all raw data and processed data. • Full access to ion correction algorithms and intermediated data. • Raw data integrity and sample identity. • Access to easy batch reprocessing, manual peak and background definition including printouts and data export. • Fully customizable and multiple exports of evaluated data to Excel other spreadsheet programs and databases (LIMS). • All printouts are fully customizable due to object oriented printout templates using the unique Isodat 2.0 Result Workshop package. • Full network compatibility with direct and fast access to Windows® tools. • Complete Isodat 2.0 system backup and retrieval within minutes using the Isodat 2.0 Version Handler. Based on the unique “Plug and Measure” concept of the new generation of Isotope Ratio MS (Finnigan DELTAplusXP, Finnigan DELTAplusAdvantage and Finnigan MAT 253), the Finnigan GC-C/TC III interface is immediately recognized and operational. Straight forward & Easy Flexible & Powerful Finnigan™ GC-C/TC III GC Interface for Compound Specific Isotope Analysis Analytical Performance Finnigan GC-C/TC III Basic Performance 10 pulses of reference gas (amplitude 3V, for H2 5V) δ notation CO2 N2 CO H2 C N 18 O 2 H 13 15 Precision (1σ) Linearity 0.06 ‰ 0.06 ‰ 0.15 ‰ 0.50 ‰ 0.02 ‰ / nA 0.02 ‰ / nA 0.04 ‰ / nA 0.20 ‰ / nA External precision for isotope ratios C, N, O, H using the GC-C or GC-TC reactors, analyte on column, (n=5), δ notation 13 15 18 C/12C N/14N O/16O D/H FID MIX 0.03% of n-C14, n-C15, n-C16 in isooctane 0.8 nmol C (10ng) e.g. 50 pmol n-C15 (11 ng) Caffeine 750 pmol (200 ng) 1.5 nmol N2 (42ng) Vanillin 1.7 nmol (200 ng) 5.0 nmol O (80ng) FID MIX 0.03% of n-C14, n-C15, n-C16 in isooctane 15 nmol H2 (30ng) 940 pmol n-C15 (200 ng) as CO2 0.2 ‰ as N2 0.5 ‰ as CO 0.8 ‰ as H2 3.0 ‰ Mass spectrometer: Finnigan DELTA series or Finnigan MAT 253 / MAT 252 Installation Requirements Thermo has designed its Finnigan GC-C/TC III interface to connect a Finnigan Trace GC to any Thermo stable isotope ratio mass spectrometer equipped for on-line analysis. Differential pumping of the He gas load is required for highest precision and sensitivity analysis. Gases Acceptance test Literature High purity helium can be taken from the GC carrier gas supply. The Finnigan GC-C/TC III interface must be supplied with high purity O2 of 99.996 % grade (or better) for GC combustion and with 1 % of H2 in He for GC high temperature conversion on δ18O determination. Reference gases (CO2, N2, CO, H2) with pressure regulators are required respectively. To use the Finnigan GC-C/TC III with CO and H2 reference gas, the laboratory must be equipped with a CO and H2 detector according to local requirements. A single test series for the precision of isotope ratios according to the above analytical performance specifications will be performed for each mode during the installation of the Finnigan GC-C/TC III interface. In combustion mode a C or N test series and in high temperature conversion mode a D or O test series will be performed. For the general purpose GC interface (Finnigan GC/GP) without furnaces the specification according to the attached preparation device will be shown. In any case the basic interface performance is shown using one of the listed gases. For publications, technical information and application flash reports please contact your local Thermo Electron specialist. More information is also available on our website www.thermo.com. Laboratory Solutions Backed by Worldwide Service and Support In addition to these offices, Thermo Electron Corporation maintains a network of representative organizations throughout the world. State-of-the-art instruments are only the beginning with Thermo Electron. Comprehensive service and support programs are offered on our products worldwide by a network of factory trained and highly qualified scientists Australia +61 2 9898 1244 • [email protected] and engineers. 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